1. Field of the Invention
The present invention relates to an apparatus and a method for handling reactor-internal equipments and, more particularly, an apparatus and a method for loading/unloading control rods, fuel supports, and control rod guide tubes into/from a boiling water reactor (referred to as "BWR" hereinafter).
2. Description of the Related Art
FIG. 10 is a fragmental sectional view showing a part of a reactor-internal structure of the BWR in an enlarged manner. As shown in FIG. 10, in the BWR, a core plate 3 is provided to a shroud 2 which is constructed integrally with a reactor pressure vessel (reactor vessel) 1. Control rod drive mechanism housings (referred to as "CRD housings" hereinafter) 4 are provided to a bottom portion of the reactor pressure vessel 1 which is located at a lower portion of the core plate 3. A control rod drive mechanism (referred to as "CRD" hereinafter) 5 is installed inside the CRD housing 4.
A control rod guide tube (referred to as "CRGT" hereinafter) 6 is provided on the CRD housing 4. The CRGTs 6 are supported to be slightly protruded upwardly from the core plate 3. A fuel support(referred to as "FS" hereinafter) 8 is detachably attached to an upper opening portion of the CRGT 6. The CRGT 6 and the FS 8 are fixed by a positioning pin 11 which is provided on the core plate 3.
A control rod (referred to as "CR" hereinafter) 7 with a cruciform lateral sectional shape is provided in the CRGT 6 to be moved vertically. A bottom end of the CR 7 is coupled to a top end of the CRD 5. The CRs 7 can be inserted into clearances between the fuel assemblies 10 from top ends of the CRGTs 6 respectively.
A top portion of the FS 8 supports a bottom portion 15 of the fuel assembly 10. Also, a top portion 12 of the fuel assembly 10 is supported by an top guide 13 which is provided to the shroud 2.
FIG. 11 is a perspective view, partially omitted, showing an example of the CRGT 6 of the BWR. As shown in FIG. 11, a plurality of CRGT orifices 32 are formed on a top end side wall of the CRGT 6.
FIG. 12 is a perspective view showing an example of the FS 8 of the BWR. As shown in FIG. 12, a cruciform through hole 9 into which the CR 7 is inserted is formed in the FS 8. Four fuel assembly sustaining holes 31, which sustain four fuel assemblies 10 respectively, are formed on a top portion of the FS 8. In addition, a plurality of fuel support orifices (referred to as "FS orifices" hereinafter) 33 are formed on a bottom side surface of the FS 8.
FIG. 13 is a perspective view showing the fuel support with pin (referred to as "Pin-FS" hereinafter) 22 of the BWR. The Pin-FSs 22 are provided to support mimic fuel assemblies (not shown) arranged in a peripheral portion of the core. This Pin-FS 22 is constructed by adding a pin 53 to the FS 8 shown in FIG. 12.
Then, if the CRs 7 are exchanged in the periodical inspection, the CRs 7 must be exchanged after the fuel assemblies 10 and the FSs 8, which are positioned at an upper location than the CRS 7, have been removed. The fuel assemblies 10 are unloaded by a refueling machine (not shown) which is installed on an operation floor (not shown), and then the CRs 7 and the FSs 8 are unloaded to outside the reactor.
As an equipment employed to execute unloading operations of the CRS 7 and the FSs 8, a CR & FS grapple (not shown) which can grasp the CR 7 and the FS 8 at the same time has been proposed. After the CRs 7 and the FSs 8 have been unloaded from the reactor by the CR & FS grapple, the exchanging operation of the CRs 7 can be performed.
In addition, there is a rare case where the CRGTs 6 must be removed. In this case, such CRGTs 6 can be removed by a CRGT grapple (not shown).
However, in the event that the unloading operations of all the CRs 7, the FSs 8, and the CRGTs 6 from the reactor and the installing operations of them into the reactor must be performed in the periodical inspection or in the preventive maintenance, etc., there have been such problems that, if the CR & FS grapple and the CRGT grapple, for example, are employed, a time required for such operations is extremely prolonged and thus an exposure dose of the operator is increased correspondingly. Further, there has been such a problem that, if the CRs 7, the FSs 8, and the CRGTs 6 are unloaded from the reactor separately, it is difficult to secure respective storage spaces for them.